Conventionally, wireless communication is performed between an RFID tag (non-contact IC label) and a reader or the like. However, when such an RFID tag is attached on an object to be adhered that is made of a metal, communication performance is lowered. In order to solve the above problem, various configurations for RFID tags have been proposed as described below.
For example, in electromagnetic induction type RFID tags which use radio waves in the 13.56 MHz band, a magnetic body (magnetic sheet) having high magnetic permeability is disposed between an antenna and an object to be adhered. Accordingly, the RFID tags can ensure a magnetic flux route between the antenna and the object to be adhered with reduced loss, and can be used on an object to be adhered that is made of a metal. Further, although communication performance is lowered, the thickness of the magnetic body may be reduced to, for example, 100 μm or less. Accordingly, thin metal-compatible RFID tags for objects to be adhered that are made of a metal can be manufactured.
On the other hand, in RFID tags using radio waves in the UHF band and the SHF band, a dielectric body or an air layer is often disposed between the antenna and the object to be adhered so as to ensure a gap between the antenna and the object to be adhered, thereby reducing the effect of the object to be adhered.
In this case, however, when a dielectric body having a thickness of 100 μm or an air layer having a thickness of 100 μm is disposed between the antenna and the object to be adhered, the RFID tags having the above configuration are strongly influenced by the object to be adhered made of a metal and fail to communicate, which is similar to the case of electromagnetic induction type RFID tags.
Therefore, it currently seems to be difficult to manufacture thin electromagnetic induction type RFID tags (having a thickness of few hundreds of μm or less).
As another type of RFID tags using radio waves in the UHF band and the SHF band, PTL 1 has proposed a non-contact IC label having a magnetic sheet disposed between the antenna and the object to be adhered.